In a statement late Wednesday, doctors reveal that McCain has been diagnosed with glioblastoma, an aggressive cancer. The statement says the 80-year-old senator and his family are reviewing further treatment, including a combination of chemotherapy and radiation.

The senator has been recovering at his Arizona home after doctors at the Mayo Clinic removed a blood clot above his left eye.

The doctors say McCain is recovering from his surgery amazingly well and his underlying health is excellent, according to the statement.

McCain was the GOP's presidential nominee in 2008. A Navy pilot, he was shot down over Vietnam and held as a prisoner for 5 ½ years.